1. Field of the Invention
The invention relates to access control in general and particularly to access control for animals on a selective basis.
2. Description of the Related Art
In recent years, specialty pet food has become big business, with foods now tailored to almost any diet according to an animal's medical condition. While the specialty diets have improved the longevity and general health of the average domestic animal, problems arise in a household where more than one domestic animal is free to roam through the house. In this case, it becomes a problem if one of those animals is to eat the specialty diet while the other animal is not. Take for example an old house cat living together with a young house cat. The old house cat may be put on a low protein high energy diet to offset the effects of aging. A common sight in a situation such as this is to find a normally functioning older cat, benefiting from the virtues of the specialty diet together with a younger cat that has a ballooning weight gain due to the fact that its metabolism is not suited to the high energy diet.
The applicant is aware of but two references which deal specifically with this problem, namely U.S. Pat. Nos. 3,897,753 and 4,036,178, both to Lee et al. In this case, the system involves the use of a rather complex control system that generates a field around a food receptacle. The field is a barrier to any animal not wearing a special collar that is provided with a conductive portion that alters the field in some predetermined manner to signal to the system that the proper animal is near, thereby disabling a shock or other signal generating device. In the converse situation, the animal not wearing the collar ventures over to the receptacle and because the animal is not wearing the special collar, the shock mechanism is not disabled. Following his appetite, the animal reaches over the lip of the receptacle, makes contact with the metallic strip and receives a shock, thereby frightening the cat away from the receptacle.
While the system appears to have the ability to distinguish between those animals entitled to access and those who are not, the system is unreasonably complex, relying on the disruption of a field to disable the alarm mechanism. In addition, the fact that this system administers a shock to repel an animal may raise concerns with some people.
There remains a need for a simplified technique of controlling access of animals and one which is more humane than that of the prior art.